A network control arrangement where path hunts through a first network are performed with reference to a second network that is topologically equivalent to the first. Path hunts through a crossover network, well-suited for implementation in the photonics domain, are performed with reference to a topologically equivalent shuffle network using a very efficient, shuffle network path hunt algorithm.

An arrangement for pooling service circuits so that they become available to a plurality of switching systems in a telecommunications network. A regional control node receives a request for a service circuit to be connected to a call. The regional control node maintains the availability status of the service circuits in a pool for the region. In response to a request for a service circuit, the regional control node selects an appropriate circuit and transmits order to the switches and the circuit to establish the proper connections among these units in order to associate the service circuit with the requesting call. Advantageously, such an arrangement permits a large pool of individually expensive service circuits to serve a large number of switching systems, thus, increasing the efficiency of utilization of these service circuits. The arrangement is also used for controlling the allocation of transmission resources to any call, thus optimizing the use of the regional transmission resources.

A method and apparatus for monitoring the load on a communications link in a common channel signalling system connecting an exchange in a telephone network to regional equipment such as a remote subscriber switch or a remote cellular base station. The length indicator field of each signal unit transmitted over the reserved channel of the communications link is monitored by the exchange to determine the number of bytes of message data being transmitted over the link during a predetermined time period. The load on the communications link is identified by taking the ratio of the determined number of bytes to the number of full value bytes capable of transmission over the communications link during an identical time period. The determined load ratio is compared to a predetermined threshold level to identify an overload condition in response to which the exchange relieves the overload by spreading the messages to other links, discarding low priority ones of the messages, or controlling message flow over the link as necessary.

A method for restoring a communication failure in a network comprises the steps of providing a predetermined order for selection of the links included in the network, searching for an alternative communication path upon a failure in communication occurring in the network, producing, at a first arbitrary node included in the alternative communication path, a first path setup message containing at least information about the number of the paths to be selected in a first link extending from the first node for setting up the alternative communication path, and an identification code of the path that is to be selected at first in the first link for establishing the alternative communication path, transmitting the first path setup message to a second node also included in the alternative communication path and connected to the first node by a second link, for affecting a setup of the connection therein. The second node selects paths with the number specified by the path setup message according to said predetermined order of selection and affects a connection to the paths in the first link according to the order of selection.

In a focal point network, adjacent nodes may agree to a relationship where one node (a focal point or server node) supplies network management services to the other node (a non-focal point or served node). A served node forwards management services data to its server node without waiting for any request. There is a risk that the nodes will become configured into a closed loop within which data, once introduced, will circulate endlessly. To eliminate this risk, a loop-detection message is generated when a node acquires a new server node and is itself a server node for other nodes. The message, which includes the originating node's name, is passed from served node to server node. Each node inspects the message. If it does not find its own name, it appends its name to the message and passes it on to its own server node. If the node does find its own name, it generates a loop-detected message that revokes the server/served relationship with the current server node.